Certain individuals require a respiratory supplement such as air, oxygen, or other gases. Such gases are freely supplied and/or supplied at controlled pressures. Such gases are also supplied through the patient's mouth and/or through the patient's nose. Nasal supply systems provide an advantage in that they are generally more convenient and less intrusive than mouth based or mouth covering devices. Despite their convenience, nasal based devices are deemed uncomfortable in light of securement straps placed across the face and/or around the head and used to secure the device to an individuals breathing cavity. Moreover, conventional cannulas do not provide a proper seal around the nares to inhibit apnea and to provide a high flow system to stimulate the patient's breathing. Hence, even with such securement straps, these nasal devices often dislodge from the breathing cavity. This is of particular concern with children, infants, or the elderly who do not understand the importance of keeping the nasal breathing device in place, whether it be a nasal CPAP or nasal cannula.
It is known to be beneficial and therapeutic to supply an individual with a sufficient amount of respiratory airway pressure in order to maintain a minimum level of air volume in the lungs. If the air volume falls below this minimum level, then the lungs may collapse, which can be extremely dangerous or even deadly to the individual. Moreover, the back pressure can increase oxygen levels in the lungs and decrease carbon dioxide levels. This will also improve PH by removal of carbon dioxide, which is an acid, from the blood. Hence, the application of such sufficient pressure, called continuous positive airway pressure (CPAP), has been found to be advantageous in maintaining a minimum air volume or lung pressure when an individual is spontaneously breathing. CPAP can be supplied through nasal attachment devices such as a nasal cannulae, or through mouth based or endotracheal devices.
A number of CPAP devices are known including endotracheal tubes, head chambers, face chambers, face masks, nasal prongs, and nasal cannula. While each type of device has advantages and disadvantages, the nasal cannula provides a comfortable alternative for providing CPAP and/or airflow assistance. Prior art nasal cannulae have been disclosed in many forms with various methods of securing the device to the nasal passageway. One such cannula assembly is disclosed in U.S. Pat. No. 3,513,844 which uses an adjustable strap that encircles an individual's head. A similar device is disclosed in U.S. Pat. No. 4,106,505 wherein the supply tubes to the cannula are hooked over an individual's ears and around the head. Even more cumbersome, U.S. Pat. No. 5,477,852 discloses a device with a headband for holding and positioning the nasal inserts and associated supply tubes. Yet another system in U.S. Pat. No. 5,271,391 discloses a cannula which is secured by applying strips of pressure sensitive adhesive tape to the supply tubes leading from each side of the cannula, thereby attaching the supply tubes to the cheeks of an individual with the cannula positioned in between.
“Bonnet” type devices are also used to hold the CPAP nasal cannulae in place. However, this method generally puts pressure on an individual's nose and upper lip thereby causing pressure necrosis in the centre of the nose. A particularly sensitive individual is a young child, infant or baby. The bonnet also fails to adequately keep the nasal prongs in position, particularly with infants who move or roll around in their crib. In a hospital or care facility setting, it is not uncommon for an attendant to discover that the CPAP device has been disconnected from a patient's nose, which can lead to apnea, desaturations, bradycardia, or hypoxia which is dangerously low oxygen levels in the blood. In practice, the tubing for these bonnet type CPAP's is draped around both sides of the patient's cheek which means that the most comfortable lying down position is on the patient's back. Pressure on the patient's cheeks caused by the securement device can make other positions uncomfortable.
Other prior art anchoring systems include adhesive devices which attach directly to the nose. U.S. Pat. No. 4,823,789 discloses a nose tube anchoring strip which has an adhesive coated sheet shaped to fit over an individual's nose and an appendage for holding a nasal-gastric tube. A similar system is found in U.S. Pat. No. 5,156,641 which has an anchoring cord adhesively attached to an individual's nose at one end and attached to hold a naso-gastric catheter at the other end. U.S. Pat. No. 5,513,635 provides a securement device with a body engagement portion which adheres across the nose of an individual with cannula engaging portions extending down therefrom. Similarly, U.S. Pat. No. 5,682,881 discloses the use of an adhesive foam pad secured to the upper lip for positioning of the cannula.
In U.S. Pat. No. 3,643,660 a unified nasal cannula comprises a hollow tubular body having an upper flat or plane surface and a pair of spaced and curved elongated tubular extensions, having exterior orifices for directing a gas flow which extensions project upwardly at an angle from the surface. Referring to FIGS. 2 and 3 we see that because the inlet 400 is from one side the prongs 402,404 may see slightly different pressures. There is also the potential for downstream prong 404 to rebreathe the expired CO2 from upstream prong 402.
In U.S. Pat. No. 5,975,077 a cannula is disclosed including an airway injecting gas in fluid communication with nostrils of a patient and aerodynamically designed passageways for both the ambient air and the injected gas to optimize the fluid flow characteristics during inhalation and exhalation of the patient.
In U.S. Pat. No. 4,774,946 a cannula is described attached to an elongated flexible tube. The nasal prongs include bulbous portions that seat and seal the nasal tubes in the nares.
In U.S. Pat. No. 5,193,532 a device is disclosed for generating by ejector action a continuous positive airway pressure (CPAP), comprising a breathing-channel which at one end opens into the atmosphere and at another end is adapted to be provided with an attachment device to the nose and/or mouth of the patient as seen in FIG. 1. The inlet is situated between a channel open to the atmosphere and open to the prongs in such a manner that the stream of fresh gas is directed mainly co-axially into the channel, producing an ejector action.
However, while these prior art systems do provide nasal CPAP they suffer from a number of disadvantages including: insufficiently securement to the patients head, potential for unbalanced pressure in each prong, and potential for rebreathing of expired CO2.